linux-kernel - Re: [sparc64] ftrace: kernel startup-tests unaligned access

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Message-ID: <20201214113123.0b44e35e@gandalf.local.home>
Date:   Mon, 14 Dec 2020 11:31:23 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Jessica Clarke <jrtc27@...c27.com>
Cc:     Anatoly Pugachev <matorola@...il.com>,
        Linux Kernel list <linux-kernel@...r.kernel.org>,
        Sparc kernel list <sparclinux@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [sparc64] ftrace: kernel startup-tests unaligned access

On Mon, 14 Dec 2020 16:28:04 +0000
Jessica Clarke <jrtc27@...c27.com> wrote:

> On Mon, Dec 14, 2020 at 11:15:12AM -0500, Steven Rostedt wrote:
> > On Mon, 14 Dec 2020 18:59:02 +0300
> > Anatoly Pugachev <matorola@...il.com> wrote:
> >   
> > > Hello!
> > > 
> > > Enabled ftrace startup tests on a sparc64 test VM/LDOM:
> > > 
> > > $ diff -u <(gzip -dc ~/dmesg/config-5.10.0.gz) <(gzip -dc /proc/config.gz)
> > > --- /dev/fd/63  2020-12-14 16:19:38.239372599 +0300
> > > +++ /dev/fd/62  2020-12-14 16:19:38.235372433 +0300
> > > @@ -2842,7 +2842,10 @@
> > >  # CONFIG_TRACEPOINT_BENCHMARK is not set
> > >  # CONFIG_RING_BUFFER_BENCHMARK is not set
> > >  # CONFIG_TRACE_EVAL_MAP_FILE is not set
> > > -# CONFIG_FTRACE_STARTUP_TEST is not set
> > > +CONFIG_FTRACE_SELFTEST=y
> > > +CONFIG_FTRACE_STARTUP_TEST=y
> > > +CONFIG_EVENT_TRACE_STARTUP_TEST=y
> > > +# CONFIG_EVENT_TRACE_TEST_SYSCALLS is not set
> > >  # CONFIG_RING_BUFFER_STARTUP_TEST is not set
> > >  # CONFIG_PREEMPTIRQ_DELAY_TEST is not set
> > >  # CONFIG_KPROBE_EVENT_GEN_TEST is not set
> > > 
> > > 
> > > Got the following results with kernel boot logs:
> > > 
> > > Dec 14 13:48:15 kernel: clocksource: jiffies: mask: 0xffffffff
> > > max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
> > > Dec 14 13:48:15 kernel: futex hash table entries: 65536 (order: 9,
> > > 4194304 bytes, linear)
> > > Dec 14 13:48:15 kernel: Running postponed tracer tests:
> > > Dec 14 13:48:15 kernel: Testing tracer function:
> > > Dec 14 13:48:15 kernel: Kernel unaligned access at TPC[552a20]
> > > trace_function+0x40/0x140
> > > Dec 14 13:48:15 kernel: Kernel unaligned access at TPC[552a24]
> > > trace_function+0x44/0x140
> > > Dec 14 13:48:15 kernel: Kernel unaligned access at TPC[552a20]
> > > trace_function+0x40/0x140
> > > Dec 14 13:48:15 kernel: Kernel unaligned access at TPC[552a24]
> > > trace_function+0x44/0x140
> > > Dec 14 13:48:15 kernel: Kernel unaligned access at TPC[552a20]
> > > trace_function+0x40/0x140  
> > 
> > Does sparc64 require 8 byte alignment for 8 byte words?  
> 
> Yes, SPARC requires natural alignment for all primitive types (and that
> even includes 8-byte alignment for 8-byte types on 32-bit SPARC as it
> has load/store pair instructions the compiler is free to use).
> 
> 

OK, that means I was misinformed about reverting the patch that forced
alignment (and the patch I posted in reply to my email, is the revert of
the revert).

If the patch I just posted works, then I'll get it ready for mainline and
stable.

Thanks!

-- Steve